Field of the Invention
The present invention relates to a developing device used in an image forming apparatus, and a process cartridge attachable to and detachable from the image forming apparatus.
The image forming apparatus is an apparatus configured to form an image on a recording medium using an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include an electrophotographic copier, an electrophotographic printer (e.g., laser beam printer, light-emitting diode (LED) printer), a facsimile machine, a word processor, and a multifunction peripheral (multifunction printer) which combines the devices described above.
The developing device is a device configured to visualize an electrostatic latent image on an image bearing member, such as an electrophotographic photosensitive drum, using a developer. The process cartridge is formed by combining a charging unit, a developing unit or cleaning unit, and an electrophotographic photosensitive drum serving as an image bearing member, so as to be attachable to and detachable from the main body of the electrophotographic image forming apparatus. The process cartridge may be formed by combining at least one of a charging unit, a developing unit, and a cleaning unit with an electrophotographic photosensitive drum, so as to be attachable to and detachable from the main body of the electrophotographic image forming apparatus. The process cartridge may be formed by combining at least a developing unit and an electrophotographic photosensitive drum, so as to be attachable to and detachable from the main body of the electrophotographic image forming apparatus.
Description of the Related Art
An image forming apparatus using an electrophotographic process, such as a printer, uniformly charges a photosensitive drum serving as an image bearing member, forms a latent image by selectively exposing the photosensitive drum to light, and visualizes the latent image with toner serving as a developer to form a toner image on the photosensitive drum. Then, the image forming apparatus performs image recording by transferring the toner image onto a recording medium, and applying heat and pressure to the transferred toner image to fix the toner image to the recording medium.
The image forming apparatus described above requires toner supply and maintenance on various processing units. To facilitate the toner supply and maintenance operation, a cartridge formed by putting together the photosensitive drum, charging unit, developing unit, and cleaning unit into a frame has been put to practical use.
In recent years, image forming apparatuses configured to form a color image by multicolor printing have been proposed. To meet demands for faster printing speeds and application to multifunction printers, an in-line type image forming apparatus has been proposed as a color image forming apparatus. The in-line type image forming apparatus includes a plurality of photosensitive drums which are designed for multicolor printing and arranged side by side in line in a horizontal direction.
Examples of the in-line type image forming apparatus including a plurality of photosensitive drums horizontally arranged include an image forming apparatus disclosed in Japanese Patent Laid-Open No. 2008-170951. This image forming apparatus has a configuration in which a plurality of photosensitive drums are arranged side by side below a transfer belt for transferring toner images, or below a recording-medium conveying belt for conveying a recording medium to which a toner image is transferred. This configuration is advantageous in that developing devices are less affected by heat from a fixing unit because, even in the main body of the image forming apparatus, the fixing unit can be placed away from the developing devices, with the transfer belt or the like interposed therebetween.
A developing device in each process cartridge is formed by combining a developing container and a toner container for containing toner. The developing container includes a developing roller for supplying a developer (toner) to an electrostatic latent image formed on a photosensitive drum, a toner supply roller for supplying toner to the developing roller, and a developer regulating member for regulating the amount of toner on the developing roller. The toner container has a blade-like stirring member and a toner opening. The toner in the toner container is conveyed by the stirring member through the toner opening to a developing chamber.